Many medical procedures require the introduction of specialized medical devices into the human heart. For example, electrical leads, such as pacemaker leads, defibrillation leads or leads used for cardioversion, and shunts or specialized catheters are frequently placed at specific locations within the heart to perform specialized cardiac procedures. Many of these medical devices, such as pacemaker leads, are very pliant and flexible. This flexibility is necessary to prevent damage, particularly to the patient's vasculature, during the period of time those products are present in the patient. However, because of this flexibility, it is quite difficult to advance these devices through the patient's vasculature into the heart without the use of some stiffening element with the device. For example, one method of stiffening certain medical devices is to introduce a stylet into the lumen of the medical device.
The typical procedure for introducing these devices into the heart requires passage through the patient's vasculature. One early approach to introduction of devices into the vasculature was to surgically cut an opening into the patient's vasculature. However, there are several disadvantages to this procedure. To address these disadvantages, percutaneous methods have been developed to create openings in the vasculature. Once an opening is created, frequently by use of a hollow needle, a dilator is usually inserted into the vasculature which gradually increases the size of the opening. The dilator has a tapered end which spreads apart the tissue at the puncture sight as it is advanced through the vasculature. Often the dilator will contain a lumen through which other medical devices may also be inserted into the vasculature.
As an example, in a typical procedure for introduction of an electrode lead into the heart, a guidewire is first introduced through the vasculature into the appropriate chamber of the heart. This process is disclosed, for example, in U.S. Pat. No. 5,488,960. With the guidewire in place, a catheter/introducer or dilator/introducer combination is then passed over the guidewire and directed into the patient's body. The catheter or dilator is then removed from the introducer. The introducer then provides a platform from which the lead may be introduced into the heart, frequently with a stylet placed within the lumen of the lead to assist in stiffening the structure of the lead and also to permit precise placement of the device within the heart.
With conventional introducers, the maximum diameter of the pacemaker lead that can be inserted is no larger than the lumen of the introducer. This limitation created a significant problem because of the nature of pacemaker leads. Frequently, the pacemaker lead's proximal end contained an electrical connector for connection to the pulse generator. Because the size of the connecter is often larger than the diameter of the lumen of conventional cardiac introducers, splittable sheaths have been designed to assist in the insertion of these electrode leads. See, for example, U.S. Pat. Nos. 4,983,168, 4,243,050 and 4,166,469. Once the introducer directs the placement of the medical device, such as an electrode lead, into the body, the splittable introducer is torn apart lengthwise as it is withdrawn from the body. By being splittable, the size of the lumen of the splittable introducer can remain relatively small as it need be no larger than is necessary for passage of the distal tip of the medical device through the lumen of the introducer. In addition, U.S. Pat. No. 5,312,355 discloses a splittable hemostatic valve that is utilized in combination with a splittable sheath for introduction of a pacemaker electrode into a patient.
While specialized medical devices are utilized throughout the human body, many have been used in the heart, in general and specifically in the coronary sinus. The coronary sinus is the largest cardiac vein in the heart and serves as a venous conduit from smaller veins within the myocardium to the right atrium. A tissue fold or primitive valve covers the coronary sinus ostium to prevent blood from backflowing into the coronary sinus as it is being pumped out of the right atrium. Located within the right atrium, generally, above the coronary sinus is an oval depression called the fossa ovalis. Between the inferior vena cava and the coronary sinus ostium is the eustaclan ridge. The location of each of these elements may vary from patient to patient.
The coronary sinus is often used for electrophysiological procedures in the heart, including both diagnostic and treatment procedures. The coronary sinus can also be used as a location for pacing both the left and right sides of the heart. Gaining access to the ostium of the coronary sinus is a very difficult procedure, especially because of the large number of similar anatomical structures located near the coronary sinus within the right atrium. It is especially difficult because these anatomical structures do not show up on a fluoroscope.
Current procedures available for introduction of devices such as pacemakers, implantable defibrillators, specialized catheters or devices used for cardioversion into the coronary sinus are frequently time consuming and difficult. To address this problem for a particular type of diagnostic catheter, U.S. Pat. Nos. 5,423,772 and 5,549,581 disclose a precurved, coronary sinus catheter, which because of its curvature, can be advanced through the patient's vasculature directly into the coronary sinus where it can be used for diagnostic and treatment procedures. U.S. Pat. No. 5,488,960 discloses a different type of device designed for use in the coronary sinus.
Accordingly, it is an aspect of this invention to disclose a device which assists in the efficient placement of medical devices particularly small, flexible medical devices, such as electrode leads, into the coronary sinus.
It is a further aspect of this invention to disclose an introducer for introducing a medical device, such as a flexible lead for use with a pacemaker, defibrillator or for cardioversion, into the coronary sinus.
Another aspect of this invention is to disclose a fixed shape introducer to be used for the introduction of medical devices into the coronary sinus.
Another aspect of the invention is to disclose a fixed shaped introducer which can be used in a process for the introduction of medical devices into the coronary sinus without using a guidewire.
Another aspect of the invention is to disclose a process for the introduction of flexible medical devices into the coronary sinus of the human heart using a precurved guiding introducer.
These and other aspects are obtained by the design of the device of the present invention and by the process disclosed herein.